This paper deals with the integration of functional (discourse-based) and formal (syntactic and statistical) phenomena in an overall linguistic explanation which accounts for the distribution of &#8216;marked&#8217; declarative sentences in the epistolary genre, where &#8216;markedness&#8217; implies deviation from the unmarked clausal pattern &#8216;(non-dummy) subject + verb (+complements)&#8217;. Discourse- and sentence-based issues such as information packaging (principle of end focus), constituent length (principle of end weight), syntactic complexity and the organisation of the sentence are investigated in a corpus of late Middle, Modern and Present-day English letters. The conclusions drawn from the analysis of the corpus data provide an interesting insight into the possibility of characterising a particular genre &#8211; letters &#8211; according to both its complexity and its informative and linguistic organisation.